1. Field of the Invention
This invention relates to instrument focusing systems and has particular reference to improvements in stops for microscope coarse focusing mechanisms.
2. Description of the Prior Art
Stopping the coarse adjustment of a microscope objective at a preselected position along its excursion has been accomplished with a spring-loaded pin attached to one member of the system and adjusted by a screw or clamp to restrict the motion of another member. The high mechanical advantage of a microscope coarse focus, however, demands very tight clamping which puts excessive strain on the focusing mechanisms.
Other methods of using end stops on the coarse focusing shaft restrict its travel to less than 360.degree. which unduly inhibit the focusing system.
It is, accordingly, an object of the invention to provide simple inexpensive and reliable stop means which overcomes the aforesaid problems and wherewith settings for stopping a coarse focusing shaft may be made with ease and simplicity.
Another object is to provide novel means for stopping one direction of turning of an instrument focusing shaft at a preselected point of rotational orientation while permitting free reverse turning and return with an assurance of accuracy in repetition of original alignment.
Another object is to accomplish the aforesaid reverse turning over greater than 360.degree. from the preselected point of alignment and return thereto.
Other objects and advantages of the invention will become apparent from the following description.